Last week I discussed genre, as, in part, a contract between writer and reader, reader presenting an itch, writer agreeing the scratch it. Writers who then refuse to scratch, but instead provide something they claim is vastly better, often fail dramatically.
Believe me, the sales figures for Brain Thief, a humorous cultural critique disguised as a science fiction novel, demonstrate what happens when readers expect one thing and get something else. Remember, if you click that link, you have been warned.
But, taking a step back, think about readers. Think about fans. Think about science fiction fans. A curve showing SF fan personalities, in terms of rationality, sociableness, intelligence, ability to read inner mental states from outwards signs of expression and posture, whatever you want, will show a skew in a certain direction. We are not as others are.
Well, our mean is not as other means are, at least. Clearly there's a huge overlap, now matter how you try to sort. But that's enough of a skew to establish an audience that tends to have a certain itch. Science fiction, the genre, evolved, as a set of conventions, tropes, and customer types that works to scratch it. And those SF fans talk to each other, form communities, write back and forth, and define their itches in ever more detail.
I doubt any other genre has a fan base that skews this far from the mean. Of all genres, SF is the most genre-y. Violate its dictates at your peril.
As I said, I know whereof I speak.